/usr/lib/x86_64-linux-gnu/libxenctrl.so is in libxen-dev 4.9.2-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libxenctrl-4.9.so
/usr/lib/x86_64-linux-gnu/libxenctrl-4.9.so